Kreutter/Costello: DC Circuits 2
Learning the Language for DC Circuits
2.1 Circuit Diagrams
A circuit diagram is a representation that uses symbols to show the components in
a circuit and how they are connected:
Part of Circuit
Wire
Sketch
Schematic Symbol
Ammeter (reads
current)
1
L
Voltmeter (reads
voltage)
Resistor
-J
Light Bulb
()
:
Battery
Ground
Use the symbols to draw a circuit for a battery, a light bulb, and a single wire.
Make sure the diagram represents a circuit that would result in a light bulb
being lit!
ter/Costello: DC Circuits 2
•
_.2 Vocabulary
liv i.
Potential Difference (voltage):
be
ç
4i
ç
4
:
f:
4
r f’c
3,
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“F
‘WI
V
K
I
.,
t
i
Current:
ntist
3,
Y
-4’
()
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‘
4
4W,
I
)t
,
I
C
flu
Resistance:
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i
I
‘j•
(1
I
1
Series Circuit:
‘F
I
‘I
I
a
u-tv
S
p.
‘j 1
14
I
Parallel Circuit:
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1’
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1eutter/Coste11o: DC Circuits 2
2.3
We
connected
can
that
learned
to
explain
the
and
Parts of the
Electric
Circuit
Battery
for
light
predict
a
bulb
light
with
phenomena
bulb
to
glow,
conducting
related
the
wires.
to
poles
two
Come
electric
up
of
with
battery
must
analogies
that
a
circuits.
Create your own analogy
?urp
Connecting
wires
W6C
Moving
Electrons
: I t1
Light
bulb,
resistor
t’ic
Observed properties of
electric circuit
Observed properties of your own analogy
When resistors are in
series (and you don’t
the voltage),
change
current
When
gIown.
resistors
are
in
(and you don’t
change the voltage),
current ç up.
parallel
V
ITh)
I
—
be
eutter/Coste1lo: DC Circuits 2
2.4 Test your Ideas For each of the following circuits below; predict the brightness of
the bulbs. Identify each circuit as series or parallel. Then, build the circuits using
real materials. Are the results consistent with the predicted outcome? Explain the
results using any of your analogies of electric phenomena.
(b)
(c)
(e)
(d)
3
Circuit
a
Results
Prediction
Explanation
t
‘
b
r
4
-
C
R
0
v
:
I
0
—
L
isfr
r
*
;;
-F
e
•reutter/Costello: DC Circuits 2
2.5 Reason
(a) Consider the following partial circuit diagrams below, and indicate whether
components between point A and point B are in parallel or in series:
A
I1
B
A
I
±±
I
AB
B
B
—
F
_;
Consider the circuit drawn below, including batteries A and B and the three light
bulbs:
B
A
(b) Indicate two sets of components (pieces) that are each connected in series.
(c) Indicate at least one set of components (pieces) that are each connected in
parallel
(4)
:
2.6 Represent and Reason
(a) Predict how the brightness of the top bulb shown in the
illustration to the right changes when you close switch 1.
a_i
2
(b) Predict how the brightness of the top bulb changes when you close switch 2 (switch 1
is open).
(c) Rate the brightness of the three bulbs when both of the switches are closed. Explain
your reasoning using any of the analogies.